The usual apparatus for measuring the speed and rotational direction of a motor shaft is a dual-channel encoder coupled to the motor shaft. A predetermined number of pulses is generated by each shaft revolution. The encoder counts the number of pulses that occur within a predetermined time period to measure the rotational speed. The direction of rotation is determined by observing which channel is leading or lagging in the respective pulse trains.
The prior method of using the dual-channel encoder to sense a motor's shaft speed and rotational direction has several disadvantages. It has many moving parts, and is an expensive system. In addition, a coupling is usually required between the motor and the encoder. Alternately, the encoder components are designed into the motor at an additional expense.
The present invention seeks to provide speed and direction sensing for a motor with one moving part.
As another of its objectives, the current invention provides the desired speed and direction of rotation for a motor shaft at a reduced cost.
The present invention does not require coupling a sensor to the motor, thus reducing wear and friction, and improving reliability and service life.